GHB, The Actions of
GHB in the Body
by John Morgenthaler and Dan Joy
GHB temporarily inhibits the release of dopamine in the brain. This may
cause increased dopamine storage, and later increased dopamine release
when the GHB influence wears off . This effect could account for the
middle-of-the-night wakings common with use of higher GHB doses, and the
general feelings of increased well-being, alertness and arousal the next
GHB also stimulates pituitary growth hormone (GH) release. One
methodologically rigorous Japanese study reported nine-fold and
sixteen-fold increases in growth hormone 30 and 60 minutes respectively
after intravenous administration of 2.5 grams of GHB in six healthy men
between the ages of twenty-five and forty. GH levels were still seven-fold
higher at 120 minutes.
The mechanism by which GHB stimulates growth-hormone release is not known.
Dopamine activity in the hypothalamus is known to stimulate pituitary
release of growth hormone, but GHB inhibits dopamine release at the same
time that it stimulates GH release. This suggests that GHB's GH-releasing
effect takes place through an entirely different mechanism.
At the same time GH is being released, prolactin levels also rise. Serum
prolactin levels increase in a similar time-dependent manner as GH,
peaking at five-fold above baseline at 60 minutes. This effect, unlike the
release of GH, is entirely consistent with GHB's inhibition of dopamine.
Other compounds which lessen dopamine activity in the brain (such as the
neuroleptic Thorazine) have been shown to result in prolactin release.
Although prolactin tends to counteract many of the beneficial effects of
GH, the sixteen-fold increases in GH probably overwhelm the five-fold
increases in prolactin.
GHB induces "remarkable hypotonia" (muscle relaxation). It is now gaining
popularity in France and Italy as an aid to childbirth. GHB causes
"spectacular action on the dilation of the cervix," decreased anxiety,
greater intensity and frequency of uterine contractions, increased
sensitivity to oxytocic drugs (used to induce contractions), preservation
of reflexes, a lack of respiratory depression in the fetus, and protection
against fetal cardiac anoxia (especially in cases where the umbilical cord
wraps around the fetus' neck).
GHB is completely metabolized into carbon dioxide and water, leaving
absolutely no residue of toxic metabolites. Metabolism is so efficient
that GHB can no longer be detected in urine four to five hours after it is
taken by injection.
GHB activates a metabolic process known as the "pentose pathway" which
plays an important role in the synthesis of protein within the body. It
also causes a "protein sparing" effect which reduces the rate at which the
body breaks down its own proteins. These properties, along with GHB's
effect on growth hormone, underlie its common use as an aid to
muscle-building and fat loss.
Anesthetic (large) doses of GHB are accompanied by a small increase in
blood sugar levels, and a significant decrease in cholesterol. Respiration
becomes slower and deeper. Blood pressure may rise or fall slightly, or
remain stable, but a moderate bradycardia (slowing of the heart) is
consistent. A slight drop in body temperature also occurs. GHB also
stimulates the release of acetylcholine in the brain.